Micro-/Nanobubble-Enhanced CO2 Biosequestration in Agricultural Systems: Mechanisms, Rhizosphere Processes and Applications

Efficient carbon transport and utilization across soil–water–plant interfaces remain a major challenge for sustainable management of agricultural ecosystems. Micro- and nanobubbles (MNBs) provide an emerging strategy to overcome these limitations by enhancing gas–liquid mass transfer and sustaining dissolved inorganic carbon (DIC) availability within the rhizosphere. By transferring CO2 delivery from the gas phase into the liquid phase, MNBs prolong carbon residence time and facilitate interactions with plant roots, microorganisms, and surrounding biogeochemical processes. This review summarizes the physicochemical characteristics of MNBs, including their high specific surface area, elevated internal pressure, and long-term stability, and discusses their role in regulating dynamic gas–liquid–solid interfacial processes. Particular attention is given to the interconnected effects of MNBs on DIC speciation, rhizosphere chemical and microbial processes, and plant physiological responses that collectively influence carbon utilization efficiency. The applications of MNB technologies are further reviewed across diverse agricultural scenarios, including seed treatment, controlled-environment cultivation, open-field irrigation, and emerging approaches for integrating industrial CO2 resources into agricultural production systems. Finally, key challenges and future perspectives are discussed, with emphasis on mechanistic understanding, scalable carbon delivery strategies, and comprehensive techno-economic and environmental assessments required for advancing MNB-enabled carbon management in sustainable agriculture.